The time required to coat a metal surface of `80 cm^(2)` with `5 xx 10^(-3) cm` thick layer of silver (density `1.05 g cm^(-3)`) with the passage of `3A` current through a silver nitrate solution is:

Options

A. 115 sec
B. 125 sec
C. 135 sec
D. 145 sec

Answer

B

Explanation

Mass of silver in coated layer = volume `xx` density
`=(80xx5xx10^(-3))xx1.05 g`
`=0.42 g`
`:' W=(ItE)/96500`
`:. T=(Wxx 96500)/(I xx E)=(0.42xx96500)/(3xx108)=125.09 sec`